Ink jet pens typically require an ink filter to be placed between the ink reservoir and the nozzle, preferably close to the nozzle, to filter out particles and impurities in the ink. These particles often arise either from poor processing of the ink prior to insertion into the pen, or from unsanitary conditions during the assembly of the pen. If a particulate of a dimension larger than an ink flow passage were to get stuck in the passage, it could slow or prevent the flow of ink to the nozzle. Thus, an effective filter prevents an early failure of the ink jet pen due to such a particulate, and prolongs its life by reducing long-term contamination.
Filters for ink jet pens have taken on many forms. For example, U.S. Pat. No. 6,254,229 to Bohorquez et al. discloses a filter member having a plurality of holes coupled to a flat microscreen filter. U.S. Pat. No. 6,234,623 to Drake discloses first and second filter arrays patterned onto layers. U.S. Pat. No. 5,537,136 to Brandon et al. discloses a filter cap including a mesh material formed into a dome-shaped configuration. U.S. Pat. No. 6,152,560 to Hollands discloses a filter element made of a sheet-like material having a curved shape. U.S. Pat. No. 5,949,458 discloses a fibrous body to act as a filter. U.S. Pat. No. 5,546,109 to Nakano discloses a flat filter member that is interposed between two thin films permeable to air.
However, as pen performance increases, a higher ink flow rate is required, thus requiring a higher effective filtration surface area of the filter media. Typically, the filters in the prior art have small effective filtration surface areas. There is thus a need for ink jet filters having a larger effective filtration surface area and, hence, a higher filtration rate.
Embodiments of the present invention provide a filter for an ink jet pen, comprising a filter material configured to attach to the pen, wherein a flow of ink through the filter material is substantially multidirectional. In a preferred aspect, an effective filtration surface area of the filter is substantially greater than any projection surface area of the filter. In another preferred aspect, the filter, which is cylindrical or rectangular in cross section, comprises a chamber at least partially bounded by the filter material, and preferably the filter material comprises more than half of a surface area of the chamber. Further, a flow direction of ink into the chamber is substantially different than a flow direction of ink from the chamber. In another preferred aspect, the filter material, which is pleated and comprises pores having a dimension substantially less than a dimension of a smallest ink flow passage in the pen, is configured to attach to the pen via an ink passage flange. In one preferred aspect, ink flows into the chamber via the flange; in another, ink flows from the chamber via the flange. The flange is attached to the filter material either by an adhesive or by melting the flange. In other preferred aspects, the chamber is configured to house a regulator, the filter comprises ribs, and the filter comprises a bag, which is preferably folded, and which comprises two sheets of filter material sealed together.
The present invention also provides for a filter for an ink jet pen, comprising a filter material configured to attach to the pen, wherein an effective filtration surface area of the filter is substantially greater than any projection surface area of the filter. Further, the filter comprises a chamber more than half bounded by the filter material and a flow direction of ink into the chamber is substantially different than a flow direction of ink from the chamber.
The present invention also provides for an ink jet pen, comprising a pen body and a filter, wherein the filter comprises a filter material for filtering ink, and wherein a flow of ink through the filter is substantially multidirectional. In a preferred aspect, an effective filtration surface area of the filter is substantially greater than any projection surface area of the filter. In another preferred aspect, the filter, which is cylindrical or is rectangular in cross section, comprises a chamber at least partially bounded by the filter material, and preferably the filter material comprises more than half of a surface area of the chamber. Further, a flow direction of ink into the chamber is substantially different than a flow direction of ink from the chamber. In another preferred aspect, the filter material, which is pleated, comprises pores having a dimension substantially less than a dimension of a smallest ink flow passage in the pen. The filter further comprises an ink passage flange to attach the filter to the pen body. In one preferred aspect, ink flows into the chamber via the flange; in another, ink flows from the chamber via the flange. The flange is attached to the filter material either by an adhesive or by melting the flange. In other preferred aspects, the pen further comprises a regulator (preferably positioned inside the chamber), the filter comprises ribs, and the filter comprises a bag, which is preferably folded, and which comprises two sheets of filter material sealed together.
The present invention also provides for a method of filtering ink in an ink jet pen, comprising flowing the ink through a filter material configured to attach to the pen, wherein a flow of ink through the filter material is substantially multidirectional. In a preferred aspect, an effective filtration surface area of the filter material is substantially greater than any projection surface area of the filter material. Further, the filter material bounds a chamber, where the chamber is more than half bounded by the filter material, and where a flow direction of ink into the chamber is substantially different than a flow direction of ink from the chamber.